The research is clear: caffeine is an effective ergogenic aid. But the impact coffee has on your body can be both good and bad.

“Caffeine, as with so many things, is fine in moderation,” says nutritionist Jennifer Medhurst. “But why should we limit it? The main reason is that caffeine increases cortisol production, and cortisol is the body’s master stress hormone; it curbs functions that would be non-essential or detrimental in a fight-or-flight situation. While some stress is good, four or five cups of stress a day for life is not so good.”

If you have too much caffeine there can be side effects

Be warned, if you drink too much coffee over a short period of time, you may experience symptoms, including (but not limited to): restlessness, anxiety, dizziness, upset stomach and insomnia.

“Coffee does have some negative side effects such as jitters, anxiety, and even fatigue,” says Medhurst – who suggests adding l-tyrosine to the mix, “to helps stabilize your mood while you enjoy the perks of a caffeine boost”.

Try a drink like Mind by Indi as an alternative to coffee prior to exercise, she says, “which combines caffeine and l-tyrosine, as well as a ton of other exercise supporting nutrients”.

People can tolerate varying amounts of caffeine

Remember, caffeine affects people in different ways. So just like some people can happily drink coffee and then fall asleep immediately, for others, caffeine will keep them wide awake and jittery at night. The same goes for exercise. You might find that you can tolerate a lot of caffeine – and be able to sip on it just before a workout class – or you might need to wait a full hour before exercising to let it digest properly.

Caffeine levels can vary hugely between cups of coffee

Some cups of coffee might not be much stronger than tea, while others could be four or five times as strong. “Different coffees will have different levels of caffeine and how you brew your coffee will also affect the caffeine levels,” adds Medhurst.

Benefits of coffee: can drinking caffeine before you exercise improve your fitness?